This study will examine both physical and neural-perceptual channel interactions that occur with stimulation of multiple channel cochlear implants. Specifically, the effects of channel interactions on percepts of stimulus detection thresholds and loudness estimation for dual-channel stimulation will be examined and quantified. In addition, a battery of speech recognition tests will be performed and correlated with the above mentioned measures of channel interaction. For all of these measurements, the degree of channel interaction will be manipulated by controlling the spatial extent of the electrical current configuration delivered to each of several cochlear implant channels. Cochlear electrode configurations will consist of monopolar (MP), bipolar (BP) with adjacent active and return electrodes within the scala tympani, and tripolar (TP) with one active electrode and two flanking return electrodes. The overall hypotheses to be tested are that channel interactions will be reduced when a spatially restricted electrical current configuration is employed and that reduction in channel interactions should lead to enhanced subject performance on speech recognition. The results of these studies could influence the development of future cochlear implant electrodes and speech processing strategies, ideally, leading to improved performance for most cochlear implant subjects.